Device for generating ultra highfrequency oscillations by means of a discharge tube



J'ZZANSMICHELPHWNG 002mm VZRBWG INVENTORS;

April 12, 1949.

DEVICE FOR GENERATING ULTRA HIGH FREQUENCY OSCILLATIONS BY MEANS OF ADISCHARGE TUBE ATTORNJEY.

Patented Apr. 12, 1949 DEVICE FOR GENERATING ULTRA HIGH- FREQUENCY OSCELLATIONS BY MEANS OF A DISCHARGE TUBE Frans Michel Penning and Cornelis Verburg, Eindhoven, Netherlands, assignors, by mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application May 9, 1946, Serial No. 668,549 In the Netherlands November 22, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires November 22, 1961 Claims. 1

This invention relates to an oscillation generating device, preferably for generating ultra-high frequency oscillations, comprising a discharge tube having produced therein a beam of electrons which is passed in succession along a velocitycontrol electrode system, a drift electrode and a second electrode system and in which the second electrode system is connected to the control electrode system via a feedback line. More particularly, the invention relates to a device in which the feedback line is constructed in the form of a transmission line comprising two conductors one of which surrounds the other and in which the feedback line is integral with the two electrode systems.

Such a device, however, presents the disadvantage that the frequency of the oscillations generated thereby cannot be altered continuously since it is governed by the dimensions of the oscillatory system formed by the said electrode system and the feedback line, the frequency of the generated oscillations being equal to the fundamental frequency of the oscillatory system or a higher harmonic thereof in accordance with the rate at which the electrons are passed along the electrode systems and hence in accordance with the direct voltage applied to the two electrode systems.

The invention has for its object to provide a device for generating oscillations having a wavelength preferably shorter than one meter and having means making it possible for the frequency of the oscillations to be varied in a simple manner between wide limits.

According to the invention, in a device of the kind to which the invention relates, this object is achieved by providing at least one of the said electrode systems with a coaxial transmission line of variable effective length.

In order that the invention may be clearly understood and readily carried into effect it will now be described more fully with reference to the accompanying drawing, in which the single figure is a cross-sectional View of one form of construction of a device according to the inven tion.

The device for generating ultra-high frequency oscillations shown in the figure comprises a discharge tube having an envelope l, preferably made of quartz, enclosing an electrode system for generating a beam of electrons. This electrode system comprises an indirectly heated cathode 2, a grid 3, an auxiliary anode 4 and an accelerating electrode 5, the two last-mentioned electrodes having applied to them a voltage making them positive relative to the cathode. At its end remote from the said electrode system the envelope l contains an electrode 8 and a collector electrode 1, the latter electrode serving to collect the electrons emitted from the cathode 2. The electrodes 6 and l have also applied to them voltages making them positive with respect to the cathode. The voltage applied to electrode 6 is preferably equal to the voltage of the electrode 5 which is positive relative to the cathode, whereas, the voltage on electrode 1 may be lower. a

In order to avoid deconcentration of the beam of electrons set up at the electrode system 2, 3, 4, 5 provision is preferably made in known manner for an axially directed magnetic field. The coils for providing this field are not shown in the figure.

On their way to the collector electrode 1 the electrons emitted from the cathode are passed through at least two electrode systems the first of which, the velocity-controlling electrode system, comprises a control electrode 8 and two bounding electrodes 9 and Ill. The bounding electrode I0 is formed by the end of the drift electrode II which forms a so-called drift space through which the beam of electrons is passed after passing the control-electrode systems. The beam of electrons is then passed along the second electrode system which comprises an electrode [2 and two bounding electrodes l3 and M the latter of which is formed by that end of the drift electrode II which is remote from the control-electrode system. The electrodes 8 to I4 have preferably supplied to them, a voltage which makes them positive relative to the cathode and which is equal to the voltage of the accelerating electrode 5 whichis positive relative to the cathode.

For generating oscillations the secondelectrode system l2, I3, I4 is coupled to the velocity control electrode system 8, 9, Ill through a feedback line comprising tubular conductors I8 and 19, the conductor l8 completely surrounding the conductor IS. The form of the line I8 is such that the conductors l8 and I9 of the feedback line are co-axial for at least part of their length.

The device described so far permits of generating oscillations whose frequency is governed by the natural frequency of the oscillatory system formed by the electrode systems 8, 9, l0 and l2, l3, l4 and the feedback line [8, l9. The operation of the device is based on velocity modulation of the electrons in the beam under the influence of a controlling voltage which is applied to the control electrode 8 of the control electrode system and on conversion of the, velocity variations thus obtained into intensity variations in the so-called drift space, said intensity variations generating an oscillation within the oscillatory system connected to the second electrode system, which oscillation is fed to the velocity control-electrode system by way of the feedback line and is efiective as a control voltage. The operation will not be given further consideration since it may be assumed to be comminly known. According to the invention, in order that it may be possible to vary the frequency of the generated oscillation the electrode system 8, 9, it is connected to a co-axial transmission line comprising conductors 2i? and 2! which in the embodiment shown are co-axi al of that part of the internal conductor it of the feedback line which adjoins the electrode 8. The length of this transmission line is variable by means of a piston 22 which makes electric contact with the internal conductor 2% and the internal conductor 2| by means of springs 23. By adjustment of the effective length of the transmission line 20, 2! by displacement of the piston 22 the frequency of the generated oscillations can be varied within wide limits.

The influence which the effective length of the transmission line 25), M exercises on the frequencyof the generated oscillations is due to the fact that the transmission line forms part of the oscillatory system which is constituted by the electrode systems 8, 9, l and l2, l3, l4 and feedback line I8, It and whose dimensions govern the frequency of the generated oscillation. Due to the presence of the transmission line 20, 2i of variable length the efiectivelength of this system, which can be looked upon as a bent-over co-axial transmission line along which stationary waves are set up, is varied and thus the frequency of the oscillations to be generated.

In the case of an alteration of the frequency of the generated oscillations the velocity at which the electrons pass past. the electrode systems is. accordingly altered in such manner that the output of the device remains a maximum.

Any adjustment of the piston 22 will result in setting up. a potential node at. the area of the piston there. being nearly a potential antinodeat the, area of the electrode system i2, i3, l t. The electric length of the. distance between the electrode system 52, I3, is and the piston 22', races ured along the feedback line, is therefore for any frequency of the oscillations to be generated n-ltimes the wavelength of the oscillations; n being a whole number.

With the device so far described an alteration of the effective length of the oscillatory system. will result in a variation of the intensity of the feedback due to the fact that the electrode system 8, 9, it is spaced from a potential antinode a distance that. varies with the frequency control.

In, order to obtain a control of the frequency of the generated oscillations without any variations of the feedback the second electrode system i2, it, M, has connected to, it. a co-axial. transmission lineof variable length 24, 25-. corresponding to the coaxial transmission line 2t, 21 and provided with an adjustable piston 2'6 having resilient contacts 21.

A device of this. kind comprising two transmis sion lines permits, on the one hand, of altering the frequency without any variation of the feedback by altering the efiective length of the two transmission lines by the same amount and, on the. other hand, ofadjusting the feedback without any variation or the frequency by lengtheningoneor the transmission lines by the" 5511 7 3 amount as that by which the other transmission line is shortened, the latter measure, however, only for those frequencies at which the spacing ween the electrode systems diverges from a half-wavelength or a multiple thereof.

In a device according to the invention the generated oscillations can be abstracted either directly, for example by means of a coupling loop, or indirectly from the oscillatory system by ab stracting energy from the beam of electrons by means of an energy abstracting electrode system which comprises the electrodes 28, 29, 3 and along which the beam of electrons passes after passing the second electrode system 52, it.

The energy abstracting electrode system 28, 2e, 38 forms part of an oscillatory system comprising two symmetrically arranged cc-axial transmission lines formed by the conductors 3i, 32 and 3 5 respectively. Similarly to the transmission lines 2%, 2i and 2 3, 253 the effective length of the transmission lines El, 192 and M can be ."iustcd as desired by means of adjustable pistons and 35 respectively provided with resilient contacts 3i til respectively.

In the oscillatory system connected to the electrode system '28, 29, it on passing this system the beam of electrons, whose intensity varies in a rhythm corresponding to the oscillations gener ated by means of the first-mentioned oscillatory system, generates oscillations Whose frequency is, in accordance with the position of the pistons 35 and 3%, equal to or a harmonic of the frequency of the oscillations generated by the oscillatory systerm formed by the electrode systems 6, 9, it and i2, i3, i i and the feedback line (8, E9. The oscillations thus generated may be derived from the oscillatory system by means of a coupling loop 39 or otherwise and may be fed to a load circuit.

By the use of two co-axial transmission lines 3|, 32 and 33, 3d connected in parallel with the electrode system 28, 25, 3 the influence of the capacity between the electrodes of the electrode system concerned is reduced by half and with a given construction of the electrodes 23, 29, 3t oscillatory system formed by these electrodes and the transmission lines 3!, 32 and 33, as can be tuned to a higher frequency than would be possible if only one of the transmission lines iii, 32 or 33, 34 were used.

In the embodiment shown in the, figure the electrode systems 8, 9, It! and l2, l3, M the drift electrode ii and the feedback line l8, l9 are external to the. envelope l of the tube in which the beam of electrons is generated.

In the device according to the invention it is, however, also possible to use a discharge tube with which the oscillatory system formed by the said electrode systems and the feedback line and a part of the co-axial transmission lines 29, 2| and 2d, 25 are arranged internally of the tube. In this case it is advantageous to arrange for a po tential node being set up approximately at the area where the tube wall intersects the transmission lines and it is consequently desirable that the eifective length of that part of the transmission lines 20, Z! and 24, 25 which is arranged internally of the tube be about a quarter or an odd multiple of a quarter of the mean wavelength of the oscil latio-ns to be generated by the device.

In a further form of construction of a device according to the invention use may be made of a tube in which at least part of the oscillatory system formed by the electrode systems 8, 9, f0 and l2, l3, l4 and the feedback line l8, l9 and of the external conductors of the co-axial transmission lines forms part of the tube wall. In an embodiment of this kind that part of the tube which contains the electrode system 2, 3, 4, 5 is preferably sealed to the edge of the bounding electrode 9 which is nearer to the cathode, Whereas that part of the tube that contains the electrodes 6 and T is sealed to the edge of the bounding electrode I3 which is remote from the cathode. In order to obtain a seal enabling a vacuum to be obtained the transmission lines 20, 2| and 24, 25 have arranged in them partitions preferably of glass or quartz. Since in this case also it is desirable that potential nodes should be set up at about the area of the parti-- tions the area of the partitions is preferably chosen in such manner that the electric length of that part of the transmission lines whose external conductor forms part of the tube Wall is about a quarter or an odd multiple of a quarter of the mean wavelength of the oscillations to be generated by means of the device.

In the last-described two embodiments the adjustable pistons 22 and 26 are preferably arranged in that part of the co-axial transmission lines which is external of the tube wall.

It is obvious that the energy-abstracting electrode system 28, 29, 30 and at least part of the transmission lines connected thereto may similarly be arranged internally of the wall or may form part of the tube wall.

A practical form of construction of the device according to the invention has been found to permit of the frequency of the generated oscillations being varied continuously within wide limits, namely, from a frequency of 600 megacycles per second (a Wave length of 50 cms.) to 1,660 megacycles per second (a wave length of 18 cms.).

We claim:

1. Apparatus for generating oscillations comprising, an electron discharge tube having means to generate an electron beam, a velocity-control electrode assembly. a second electrode assembly, a drift electrode member coupled to said assemblies, said velocity-control and second electrode assemblies each comprising a bounding electrode. an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said assemblies and said member being arranged along the path of said electron beam, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor Within said tubular conductor, and means comprising a coaxial transmission line having an adjustable effective length and having the inner conductor thereof coupled to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member to vary continuously the frequency of the generated oscillations.

2. Apparatus for generating oscillations comprising an electron discharge tube having means to generate an electron beam, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member coupled to said assemblies, said velocity-control electrode assembly comprising a bounding electrode, one end portion of said drift electrode member and a control electrode interposed between said bounding electrode and said end portion of said drift electrode member, said assemblies and said member being arranged along the path of said electron beam, a transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, and means comprising a coaxial transmission line having an adjustable efiective length and having the inner conductor thereof coupled to the control electrode of said velocity-control electrode assembly and having the outer conductor coupled to said bounding electrode and said end portion of said drift electrode member to vary continuously the frequency of the generated oscillations.

3. Apparatus for generating oscillations comprising an electron discharge tube having means to generate an electron beam, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member coupled to said assemblies, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said assemblies and said member being arranged along the path of said electron beam, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising an outer tubular conductor and an inner conductor within said outer tubular conductor, said inner conductor being coupled at each end to the central electrode of the respective electrode assembly, and a coaxial transmission line having an adjustable effective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction of the inner conductor of said concentric transmission line and the central electrode and coupled to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member selectively to vary continuously the frequency of the generated oscillations.

4. Apparatus for generating oscillations comprising and electron discharge tube having means to generate an electron beam, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member coupled to said assemblies, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said assemblies and said member bein arranged along the path of said electron beam, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising an outer tubular conductor and an inner conductor Within said outer tubular conductor, said inner conductor being coupled at each end to the cen tral electrode of the respective electrode assembly, and a coaxial transmission line having an adjustable short circuiting member interposed between the inner and outer conductors thereof to vary the efiective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of said inner conductor of said concentric transmissionline and'the central electrode and'coupled'toithe central electrode of one of said electrode assemblies and having the outer conductor coupled tosaid'bounding electrode and the respective end portion of said drift electrode member to vary continuously the frequency of the generated oscillations.

5. Apparatus for enerating oscillations comprising an electron discharge tube having means to generate an electron beam and in the order indicated a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity control electrode and said sec ond electrode assemblies, and a third electrode assembly, said velocity-control and second electrode assemblies each comprising a bounding electrode, anend portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, saidasscmblies and said member being arranged alon -the path of said electron beam, a concentric transmission line coupling said velocity-control elec rode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said-tubular conductor, means comprising a coaxial transmission line having an adjustable effec ive length and having the inner conductor thereof coupled to the central electrode ofone'of said electrode assemblies and hayingthe outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to' vary continuouslythe frequency and the amplitude ofzthe generatedoscillations, and an output deriving means'ooupled to said third elec trode assembly.

6. Apparatus for generating oscillations comprisil an-electron-discharge tube having means to'generate an electron beam and in the order indicated a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said'second electrode assemblies and a third electrode assembly, said velocity-control and second electrode assemlies each comprising a bounding electrode, an end portion. of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, said assemblies and said member being arranged alon the path of said electron beam, a concentric transmission line coupling said velocity-control. electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, means comprising a coaxial transmission line having an adjustable effective length and having the inner conductor thereof connected to the central electrode of one of said velocity control and second electrode assemblies, and the outer conductor coupled to said housing electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, means comprising second and third co- ;axial transmission lines having any adjustable efiective length "and havin the inner conductors thereof coaxial with respect to each other and coupled'to the central electrode of said third electrode assembly andhaving the outer conductors thereof coupled to and symmetrically arranged with respect to the bounding electrodes of said third electrode assembly, and an output deriving means coupled to said third electrode assembly.

7. Apparatus for generating oscillations comprising, an electron discharge tube having means to generate an electron beam and within said'tube in the order indicated a velocity-control electrode assembly, a second electrode assembly, a drift electrode member coupling said assemblies, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a centralelectrode interposed between said bounding electrocle and the respective end portion of said drift electrode member, said assemblies and said member being arranged along the path of said electron beam and a concentric transmission ,line coupling said Velocitycontrol electrode-assembly to said second electrode assembly, said transmission line comprising an outer tubular conductor and an inner concluctor within said outer tubular conductor, said inner conductor being coupled at each end to the central electrode of the respective electrode assembly, and a coaxial transmission line having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of said inner conductor and the central electrode and coupled to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, said coaxial 'transmissionlinehaving a portion within said tube, the electrical length of said portion being substantially an odd number of quarter wave-lengths of the mean Wavelength of the generated oscillations.

8. Apparatus for generating oscillations comprising an electron discharge tube having an envelope and a heater, a cathode, a grid, an auxiliary anode, an accelerating electrode, a further electrode-and a collector electrode within said envelope, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said second electrode assemblies, a third electrode assembly, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed 'therebetween, said assemblies comprising a, portlon of the envelope of said electron discharge tube, a, concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, first and second coaxial transmission lines coupled to each of said velocity-control and Second electrode assemblies, each of said coaxial transmission lines having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of said inner conductor of said concentric transmission line and the central electrode and coupled to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, third and fourth coaxial transmission lines coupled to and symmetrically arranged with respect to said third electrode assembly, each of said third and fourth coaxial transmission lines having an adjustable annular member interposed between ,the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coupled to the central electrode of said third electrode assembly, and the outer conductor coupled to said bounding electrodes of said third electrode assembly, thereby to vary continuously the resonant frequency of said third electrode assembly, and an output deriving means coupled to said third electrode assembly.

9. Apparatus for generating oscillations comprising an electron discharge tube having an en velope and a heater, a cathode, a gird, an auxiliary anode, an accelerating electrode, a further electrode and a collector electrode within said envelope, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said second electrode assemblies, a third electrode assembly, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, said assemblies comprising a portion of the envelope of said electron discharge tube, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, first and second coaxial transmission lines coupled to each of said velocity-control and second electrode assemblies, each of said coaxial transmission lines having an adjustable annular member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of said inner conductor of said concentric transmission line and the central electrode and connected to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, third and fourth coaxial transmission lines coupled to and symmetrically arranged with respect to said third electrode assembly, each of said third and fourth coaxial transmission lines" having an adjustable annular member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof connected to the central electrode of said third electrode assembly, and the outer conductor coupled to said bounding electrodes of said third electrode assembly, thereby to vary continuously the resonant frequency of said third electrode assembly, each of said first, second, third and fourth coaxial transmission lines having a portion within the envelope of said discharge tube, the electrical length of said portion being substantially an odd number of quarter wavelengths of the mean wavelength of the generated oscillations, said adjustable annular member of each of said coaxial transmission lines being external to the envelope of said dis-- charge tube, and an output deriving means coupled to said third electrode assembly.

10. Apparatus for generating oscillations comprising an electron discharge tube having an envelope and a heater, a cathode, a grid, an auxiliary anode, an accelerating electrode, a further electrode and a collector electrode within said envelope, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said second electrode assemblies, a third electrode assembly, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, said assemblies and said member surrounding said electron discharge tube, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, first and second coaxial transmission lines coupled to each of said velocity-control and second electrode assemblies, each of said coaxial transmission lines having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of said inner conductor of said concentric transmission line and the central electrode and coupling to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, third and fourth coaxial transmission lines coupled to and symmetrically arranged with respect to said third electrode assembly, each of said third and fourth coaxial transmission lines having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coupled to the central electrode of said third electrode assembly, and the outer conductor coupled to said bounding electrodes of said third electrode assembly, thereby to vary continuously the frequency of the oscillations produced in said third elec- 11 trode assembly, and an output deriving means coupled to said third electrode assembly.

11. An electron discharge tube for generating oscillations comprising, an envelope, means to generate an electron beam, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member coupled to said assemblies, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said assemblies and said member being arranged along the path of said electron beam, said assemblies forming a portion of said envelope, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, and means comprising a coaxial transmission line having an adjustable efiective length and having the inner conductor thereof coupled to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member to vary continuously the frequency of the generated oscillations, said coaxial transmission line having a portion within said envelope and having means to effect a vacuum tight seal within said envelope.

12. An electron discharge tube for generating oscillations comprising, an envelope, means to generate an electron beam, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member coupled to said assemblies, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said assemblies and said member being arranged along the path of said electron beam, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising an outer tubue lar conductor and an inner conductor within said outer tubular conductor, said inner conductor being coupled at each end to the central electrode of the respective electrode assembly, and a coaxial transmission line having an adjustable eifec tive length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of the inner conductor of said concentric transmission line and the central electrode and coupled to the central electrode of one of said electrode as semblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member to vary continuously the frequency of the generated oscillations.

13. An electron discharge tube for generating oscillations comprising, means to generate an electron beam and in the order indicated a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said second electrode assemblies, a third electrode assembly, said velocity-control and second electrode assemblies each comprising a bounding electrode, an .end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, said assemblies and said member being arranged along the path of said electron beam, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, means comprising a coaxial transmission line having an adjustable effective length and having the inner conductor thereof coupled to the central electrode of one of said electrode assemblies, and the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, and an output deriving means coupled to said third electrode assembly,

14. An electron discharge tube for generating oscillations comprising, an envelope and a heater, a cathode, a grid, an auxiliary anode, an accelerating electrode, a further electrode and a collector electrode within said envelope, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said second electrode assemblies, a third electrode assembly, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, said assemblies comprising a portion of said envelope, a concentric transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, first and second coaxial transmission lines coupled to each of said velocity-control and second electrode assemblies, each of said coaxial transmission lines having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of said inner conductor of said concentric transmission line and the central electrode and coupled to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, third and fourth coaxial transmission lines coupled to and symmetrically arranged with respect to said third electrode assembly, each of said third and fourth coaxial transmission lines having an adjustable annular member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coupled to the central electrode of said third electrode assembly, and the outer conductor coupled to said bounding electrodes of said third electrode assembly, thereby to vary continuously the resonant frequency of said third electrode assembly, each of said first, second, third and fourth coaxial transmission lines having a portion within said envelope, the electrical length of said portion being substantially an odd number of quarter wavelengths of the mean wavelength of the generated oscillations, and an output deriving means coupled to said third electrode assembly.

15. An electron discharge tube for generating oscillations comprising, an envelope and a heater, a cathode, a grid, an auxiliary anode, an accelerating electrode, a further electrode and a collector electrode Within said envelope, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said second electrode assemblies, a third electrode assembly, said velocity-control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, said assemblies and said member surrounding said envelope, a concentric transmission line coupling said ve1ocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, first and second coaxial transmission lines coupled to each of said velocity-control and second electrode assemblies, each of said coaxial transmission lines having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coaxial with the inner conductor of said concentric transmission line at the junction point of said inner conductor of said 14 concentric transmission line and the central electrode and coupling to the central electrode of one of said electrode assemblies and having the outer conductor coupled to said bounding electrode and the respective end portion of said drift electrode member, thereby selectively to vary continuously the frequency and the amplitude of the generated oscillations, third and fourth coaxial transmission lines coupled to and symmetrically arranged with respect to said third electrode assembly, each of said third and fourth coaxial transmission lines having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coupled to the central electrode of said third electrode assembly, and the outer conductor coupled to said bounding electrodes of said third electrode assembly, thereby to vary continuously the frequency of the oscillations produced in said third electrode assembly, and an output deriving means coupled to said third electrode assembly.

FRANS MICHEL PENNING. CORNELIS VERBURG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,169,396 Samuel Aug. 15, 1939 2,200,962 McArthur May 14, 1940 2,222,898 Fraenckel Nov. 26, 1940 2,312,919 Litton Mar. 2, 1943 2,400,753 Haeff May 21, 1946 2,425,748 Llewellyn Aug. 19, 1947 

